Put the bridle on his head, tightening all straps. Praise the goat and give him a treat.
Take him for a walk while he's wearing the bridle. Do this every day for a week so he can get used to wearing the bridle.
After he's gotten used to the bridle, attach the reins. Take him for a walk and hold the reins so he can get used to them. Now he is ready for both.
After your goat is used to the bridle, get him used to wearing a harness. The first time you put the harness on him, put his collar and bridle on first. To train him to use a harness, take the following steps:
Let him sniff and mouth the harness so he gets used to it.
Put the harness on him. Tighten the cinch strap, and then fasten the breast strap, and finally fasten the rump strap. Praise the goat and give him a treat.
Take him on a walk, using the collar to attach the lead. Give your goat several opportunities to get used to wearing the harness.
After he has gotten used to the harness, attach the lead to the harness instead of the collar. Intermittently, gently pull on the harness to simulate the feeling of a cart being pulled. Praise the goat and give a treat.
Take your goat on a walk while he is wearing the harness and bridle with reins, and teach him to stop, go, and turn to the left and right. When you want him to stop, say "Whoa" or "Stop." Pull the reins if your goat doesn't stop. Say "Go" or "Walk" when you want him to go and "Left" to go left and "Right" to go right. Practice these commands every day for a week or so, rewarding your goat when he complies, until he gets it.
Practice with a travois. Before you get a real cart, you need to simulate a cart in a safer way. Attach a travois to the harness and take your goat through the commands. To make a travois, get two long poles and a shorter pole and lash them together into a triangular shape. Practice with a travois for a week or so before attaching your goat to a cart or wagon.
Attach your goat to a cart. Let your goat look at and smell the cart. When he loses interest in it, hook him up and go.
The ideal harness goat is energetic, intelligent, and friendly.
Generally, a goat can pull about twice his weight, which includes the harness and cart.
I have read that Nubians and Boers are not ideal goats because they are stubborn and lazy, and that Oberhaslis are the best. I have no experience with cart goats, although I want one terribly.